P10 - Forces & Motion Flashcards
What is stopping distance?
total distance it takes for the car to stop
What is thinking distance?
distance car travels during driver’s reaction time
What is braking distance?
distance car travels from driver braking -> car stopping
How can you calculate stopping distance?
thinking distance + braking distance
What affects stopping distance?
speed of vehicle
What factors can affect thinking distance (reaction time)?
tiredness, drugs, alcohol ↑ thinking distance
What factors can affect braking distance?
- wet/icy conditions reduce friction between tyres & road
- worn tyres
- worn brakes
↑ braking distance
When a car brakes, what is the kinetic energy converted into? What does this cause?
thermal engy -> temp. of brakes ↑
The greater the speed of the vehicle….
greater braking forced needed to stop car
What is the law of conservation of momentum?
total momentum before = total momentum after
In terms of momentum, if time is shorter what is greater?
force
In terms of momentum, if time is longer what is smaller?
force
How do crumple zones, air bags & seatbelts etc. reduce injury/damage?
- increase amnt of time taken for a collision to occur
- this reduces rate of change of momentum
- this decreases maximum force applied
- reduces chance of damage or injury
Do non moving objects have momentum?
no
What is the unit for momentum?
kg m/s
